Three New Three-Dimensional Frameworks Based on Hepta‑, Hexa‑, and Pentanuclear Cobalt Clusters Derived from Substituted Isophthalic Acids: Synthesis, Structures, and Magnetic Properties

Three new cluster-based cobalt/carboxylate frameworks, formulated as {[H₃O]­[Co^II₇­(μ₃-OH)₃­(MeO-ip)₆­(H₂O)₃]­·4.5H₂O}_<i>n</i> (<b>1</b>), {[Co^II₆­(μ₃-OH)₂­(Bu^t-ip)₄­(Bu^t-Hip)₂­(H₂O)₂]­·2CH₃CN}_<i>n</i> (<b>2</b>), and {[Co^II₅(Me-ip)₄­(Me-Hip)₂­(H₂O)₄]­·6H₂O}_<i>n</i> (<b>3</b>) (MeO-H₂ip = 5-methoxyisophthalic acid, Bu^t-H₂ip = 5-<i>tert</i>-buthylisophthalic acid, and Me-H₂ip = 5-methylisophthalic acid) have been synthesized by the hydro­(solvo)­thermal reactions of Co₂(CO)₈ with the corresponding isophthalic acids in CH₃CN, Pr^<i>i</i>OH, and water. Single-crystal X-ray diffraction studies reveal that <b>1</b> and <b>2</b> both exhibit a three-dimensional (3D) <b>pcu</b> net based on hepta- and hexanuclear cobalt hydroxyl clusters {Co^II₇(μ₃-OH)₃} and {Co^II₆(μ₃-OH)₂}, respectively. Compound <b>3</b> is a 3D porous framework with an eight-connected <b>bcu</b> topology constructed from a pentanuclear cobalt cluster. It has been found that the structures of cobalt clusters in these compounds largely depend on the substituents on isophthalic acids. The magnetic studies indicate that both <b>1</b> and <b>2</b> show spin-canting antiferromagnetism, while <b>3</b> exhibits a magnetocaloric effect (MCE). The resulting entropy change of <b>3</b> is 13.23 J kg^–1 K^–1 for Δ<i>H</i> = 80 kG at 4 K

Synthesis and Structure of Two Acentric Heterometallic Inorganic–Organic Hybrid Frameworks with Both Nonlinear Optical and Ferroelectric Properties

Solvothermal reactions of Cd­(NO₃)₂·4H₂O with aromatic polycarboxylic acids in the presence of sodium nitrate led to two acentric three-dimensional (3D) heterometallic inorganic–organic hybrid frameworks, namely, [Me₂NH₂]­[Cd₂Na₃(2,4-PYDC)₄]·2H₂O (<b>1</b>) and [Me₂NH₂] [CdNa­(OH-<i>m</i>-BDC)₂(H₂O)₂]·2H₂O (<b>2</b>) (2,4-H₂PYDC = 2,4-pyridinedicarboxylic acid, OH-<i>m</i>-H₂BDC = 5-hydroxyisophthalic acid). The framework of <b>1</b> is constructed by a 3D inorganic Cd–Na connectivity, which resembles a concrete reinforcement structure and features a {CdNa}_<i>n</i> rod-shaped chain, a {CdNa₂}_<i>n</i> helical chain, and a 20-membered {Cd₆Na₁₄} ring. Compound <b>2</b> is built up by one-dimensional inorganic {CdNa}_<i>n</i> rod-shaped chains which are further connected by OH-<i>m</i>-BDC^2– ligands, affording a 3D polymeric framework. Compounds <b>1</b> and <b>2</b> crystallize in acentric space groups, and both display powder second harmonic generation efficiencies approximately 0.8 and 0.7 times, respectively, than that of the potassium dihydrogen phosphate (KDP) powder. In addition, they also exhibit luminescence and potential ferroelectric properties

Synthesis and Structure of Two Acentric Heterometallic Inorganic–Organic Hybrid Frameworks with Both Nonlinear Optical and Ferroelectric Properties

Solvothermal reactions of Cd­(NO₃)₂·4H₂O with aromatic polycarboxylic acids in the presence of sodium nitrate led to two acentric three-dimensional (3D) heterometallic inorganic–organic hybrid frameworks, namely, [Me₂NH₂]­[Cd₂Na₃(2,4-PYDC)₄]·2H₂O (<b>1</b>) and [Me₂NH₂] [CdNa­(OH-<i>m</i>-BDC)₂(H₂O)₂]·2H₂O (<b>2</b>) (2,4-H₂PYDC = 2,4-pyridinedicarboxylic acid, OH-<i>m</i>-H₂BDC = 5-hydroxyisophthalic acid). The framework of <b>1</b> is constructed by a 3D inorganic Cd–Na connectivity, which resembles a concrete reinforcement structure and features a {CdNa}_<i>n</i> rod-shaped chain, a {CdNa₂}_<i>n</i> helical chain, and a 20-membered {Cd₆Na₁₄} ring. Compound <b>2</b> is built up by one-dimensional inorganic {CdNa}_<i>n</i> rod-shaped chains which are further connected by OH-<i>m</i>-BDC^2– ligands, affording a 3D polymeric framework. Compounds <b>1</b> and <b>2</b> crystallize in acentric space groups, and both display powder second harmonic generation efficiencies approximately 0.8 and 0.7 times, respectively, than that of the potassium dihydrogen phosphate (KDP) powder. In addition, they also exhibit luminescence and potential ferroelectric properties

Unusual High Thermal Stability within a Series of Novel Lanthanide TATB Frameworks: Synthesis, Structure, and Properties­ (TATB = 4,4′,4″-s-Triazine-2,4,6-triyl-tribenzoate)

A series of multifunctional lanthanide-organic frameworks Ln­(TATB)­(H₂O) (Ln = Y <b>1</b>, Eu <b>2</b>, Gd <b>3</b>, Tb <b>4</b>, Dy <b>5</b>, Ho <b>6</b>, and Er <b>7</b>; TATB = 4,4′,4″-s-triazine-2,4,6-triyl-tribenzoate) with an unprecedented (4,8)-connected topology have been synthesized and characterized. The structures of these compounds were determined by single crystal X-ray diffraction and their thermal stability, sorption, as well as luminescent and magnetic properties were also investigated. Compounds <b>1</b>–<b>7</b> are isomorphic and present an open non-interpenetrated three-dimensional microporous framework constructed by infinite dinuclear-based, rod-shaped lanthanide-carboxylate secondary building units (SBUs) which arranged in nearly mutually perpendicular directions and interwoven by TATB linkers. All these compounds exhibit very high thermal stability and are stable up to 550 °C. The pore characteristics and gas sorption properties of these compounds were studied by experimentally measuring different gases (CO₂, N₂, and H₂) and different solvent molecules (H₂O and CH₃OH). The luminescent properties of compounds <b>1</b>–<b>7</b> in the solid state were investigated. The results show that <b>2</b> and <b>4</b> exhibited relatively high quantum yields and lifetime values, suggesting that they could be good candidates for light-emitting diodes (LEDs) and light applications. The variable-temperature magnetic studies show that the magnetic interaction between the Ln­(III) ions in <b>2</b>–<b>7</b> was mainly due to the antiferromagnetic coupling as well as the depopulation of the Stark levels. The spin–orbit coupling parameter λ for Eu­(III) (472 cm^–1) has been obtained for <b>2</b>. The in-phase and out-phase signals <i>χ′</i>_M<i>T</i> and <i>χ″</i>_M of <b>5</b> exhibit frequency dependence

Unusual High Thermal Stability within a Series of Novel Lanthanide TATB Frameworks: Synthesis, Structure, and Properties­ (TATB = 4,4′,4″-s-Triazine-2,4,6-triyl-tribenzoate)

A series of multifunctional lanthanide-organic frameworks Ln­(TATB)­(H₂O) (Ln = Y <b>1</b>, Eu <b>2</b>, Gd <b>3</b>, Tb <b>4</b>, Dy <b>5</b>, Ho <b>6</b>, and Er <b>7</b>; TATB = 4,4′,4″-s-triazine-2,4,6-triyl-tribenzoate) with an unprecedented (4,8)-connected topology have been synthesized and characterized. The structures of these compounds were determined by single crystal X-ray diffraction and their thermal stability, sorption, as well as luminescent and magnetic properties were also investigated. Compounds <b>1</b>–<b>7</b> are isomorphic and present an open non-interpenetrated three-dimensional microporous framework constructed by infinite dinuclear-based, rod-shaped lanthanide-carboxylate secondary building units (SBUs) which arranged in nearly mutually perpendicular directions and interwoven by TATB linkers. All these compounds exhibit very high thermal stability and are stable up to 550 °C. The pore characteristics and gas sorption properties of these compounds were studied by experimentally measuring different gases (CO₂, N₂, and H₂) and different solvent molecules (H₂O and CH₃OH). The luminescent properties of compounds <b>1</b>–<b>7</b> in the solid state were investigated. The results show that <b>2</b> and <b>4</b> exhibited relatively high quantum yields and lifetime values, suggesting that they could be good candidates for light-emitting diodes (LEDs) and light applications. The variable-temperature magnetic studies show that the magnetic interaction between the Ln­(III) ions in <b>2</b>–<b>7</b> was mainly due to the antiferromagnetic coupling as well as the depopulation of the Stark levels. The spin–orbit coupling parameter λ for Eu­(III) (472 cm^–1) has been obtained for <b>2</b>. The in-phase and out-phase signals <i>χ′</i>_M<i>T</i> and <i>χ″</i>_M of <b>5</b> exhibit frequency dependence